The HSE says its priority is to roll out the Moderna vaccine as soon as possible but it depends on supply.
GP teams will receive the first doses of it today at three mass vaccination centres in Galway, Dublin and Portlaoise.
1,800 GPs and nurses will be vaccinated across the three centres today.
Immunology expert, Professor Kingston Mills, says Moderna will be easier to store and use as it can be stored at minus 20 instead of minus 80.
He also thinks the new HSE step to give people the second dose of the Pfizer vaccine 28 days after the first is the right move: